Gas turbine unit for generating mechanical energy and compressed air

ABSTRACT

A gas turbine aggregate, especially an auxiliary unit for aircrafts which is intended to produce both mechanical energy and compressed air for loads, and in which a line branching off from the compressed air line that is supplied with compressed air from the compressor, leads to an air turbine which, in its turn, is connected with the output shaft of the gas turbine either directly or indirectly; the branch line from the compressed air line to the air turbine is provided with a valve to enable selective opening and closing of the branch line.

O Umted States Patent 1151 3,659,417 Grieb 1451 May 2, 1972 54] GASTURBINE UNIT FOR GENERATING 2,483,073 9/1949 Strub ..60/39. 1 a cMECHANICAL NE Y AND 2,541,625 2/1951 Webster ..74/661 COMPRESSED AIR2,618,431 11/1952 Walker ...60/39.18 C 3,500,636 3/1970 Craig ..60/39.18B [72] Inventor: Hubert J- Grieb, Stuttgart-Botnang, Germany FOREIGNPATENTS OR APPLICATlONS [731 Assignefi Ak'ienflmllschaf'r suttgan-885,311 5/1943 France ..60/39.18 c Germany 493,174 10/1938 Great Britain..60/39.18 c [22] Filed: Aug. 8, 1969 [21] Ap pl. No.: 848,461 PrimaryExaminer--Doug1as Hart Attorney-Craig, Antone11i& Hill [30] ForeignApplication Priority Data Aug. 3, 1968 Germany ..P 17 51 851.3 [57]ABSTRACT A gas turbine aggregate, especially an auxiliary unit for air-[52] US. Cl. ..60/39.07, 60/39.]8 C, 98/].5 crafts which is intended toproduce both mechanical energy [51 III. C] ..F 02c 7/02, 864d 13/02 andcompressed hfor loads, and i which a i branching ff [58] Fleld of Search...60/39.18, 39.18 B, 39.18 C, from the compressed i line that isSupphed with compressed 60/102 39-07; 74/661; 415/27 28; 417/28 2801 airfrom the compressor, leads to an air turbine which, in its 408; 98/15;244/59 turn, is connected with the output shaft of the gas turbineeither directly or indirectly; the branch line from the com- 1References Cited pressed air line to the air turbine is provided with avalve to UNITED STATES PATENTS enable selective opening and closing ofthe branch line. 2,618,470 1 H1952 Brown ..60/39.07 11 Claims, 2 DrawingFigures GAS TURBINE UNIT FOR GENERATING MECHANICAL ENERGY AND COMPRESSEDAIR The present invention 'relates to a gas turbine aggregate for theproduction of v mechanical energy and compressed air. Such type ofaggregates or units are. provided with tapping points or places wherecompressed air is removed, within the area of the compressor housingthereof. Compressed air, that is not needed, is thereby lost by blowingoff into the atmosphere. With gas turbine units which frequently have togive ofi only shaft-power, such as, for example, auxiliary aggregates orunits for aircrafts, an uneconomic operation results therefrom.

It is the aim of the present invention to eliminate the losses whichresult by the un-needed compressed air. This is realized in that from acompressed air line fed by the compressor of the gas turbine branchesoff a line adapted to be closed and leading to an air turbine which isoperatively connected either directly or indirectly with the outputshaft of the gas turbine. This permits a far-reaching regaining of theenergy of the compressed air supplied by the compressor but not used ,bythe load. The rate of air flow through the compressor and through thefollowing gas turbine sections is not influenced thereby which actsfavorably on the operation of the unit.

If the compressed air is not removed downstream of the compressor, thenthe pressure condition of the gas turbine process adjusts or conformsitself to that of the demanded compressed air. Since the pressureconditions demanded by the load are generally very low, an unfavorablethermodynamic process with high fuel consumption and low specific outputresults simultaneously therewith from such an arrangement.

These disadvantages are avoided according to the present invention by agas turbine which includes a multi-stage compressor consisting of alow-pressure section and of a high-pressure section with the compressedair line branching ofi downstream of the low-pressure section. The airsupplied by the high-pressure section to the gas turbine therebypossesses a pressure condition or pressure ratio that is higher andtherewith favorable from the point of view of thermodynamics of thedrive unit, which is independent of that of the given-off compressedair. An optimum thermodynamic cycle process can be determined therebywhich results in a minimum fuel consumption and a high specific output.Furthermore, as a result thereof, slight structural expenditures inrelation to the I output can be achieved thereby.

A particularly advantageous aggregate results according to the presentinvention by a transmission consisting of at least two spur gear wheelswhich mesh with a third spur gear whereby the output shaft of the gasturbine and the drive shaft of a working machine, for example, of acurrent-generator, are connected with one gear each of the transmission.In this manner, the rotational speed of the air turbine can be soselected that the air turbine operates with a high efficiency.Furthermore, by the selection of the transmission ratio a suitablerotational speed for the working machine or load can be determined.

Accordingly, it is an object of the present invention to provide a gasturbine aggregate of the type described above which eliminates by simplemeans the aforementioned shortcomings and drawbacks encountered in theprior art.

Another object of the present invention resides in a gas turbine unit,especially an auxiliary unit, which assures economical operation underall operating conditions.

A further object of the present invention resides in a gas turbine unitintended to produce shaft-power as well as compressed air, in which theloss of energy in case of non-use of the compressed air is minimized.

Still a further object of the present invention resides in a gas turbineunit of the type described above in which the rate of air flow throughthe compressor and the following gas turbine section is not influencedby the changes in load in the compressed air line.

Another object of the present invention resides in a gas turhighspecific output but also a cycle with optimum theremodynarnicconditions.

These and further objects, features and advantages of the presentinvention will become more obvious from the following description whentaken in connection with the accompanying drawings which show, forpurposes of illustration only, embodiments in accordance with thepresent invention, and wherein:

FIG. 1 is a schematic view of a gas turbine aggregate in accordance withthe present invention; and

FIG. 2 is a schematic view similar to FIG. 1 but showing a secondembodiment in accordance with the present invention.

Referring now to the drawings, the gas turbine unit is essentiallycomposed of a gas turbine generally designated by reference numeral 1with a place 2 for the removal of the compressed air, of an air turbine3, of a current generator or similar load 4 and of a multi-input gearassembly generally designated by reference numeral 5.

The gas turbine is constructed as single-shaft turbine. A compressorgenerally designated by reference numeral 7 with a low-pressure section8 and a high-pressure section 9 as well as a turbine 10 are secured onthe shaft 6. Reference numeral 11 designates the combustion chamber withconventional fuel injection and ignition devices. An arrow 12 indicatesthe air inflow at the input of the compressor 7. Reference numerals l3and 14 designate channels which connect the output of the compressor 7with the combustion chamber 11 and the combustion chamber 11 with theinlet of the turbine 10. A line 15 leads from the turbine 10 to asilencer or mufi'ler 16 from which the gases flow into the atmosphere inthe direction of the arrow 17.

A gear wheel 19 of the common, multiple input transmission 5 is mountedon the output shaft 18 of the gas turbine l. A gear wheel 20 which issecured on the output shaft 21 of the air turbine 3 meshes with the gearwheel 19. A further gear wheel 22 which together with the gear wheel 19forms a speed reduction, is mounted on the input shaft 23 of the currentgenerator 4 which supplies the power supply of the aircraft withcurrent.

A line 24 leads from the tapping point 2 for the compressed air, whichis arranged downstream of the low-pressure section 8 of the compressor 7in the direction of the arrow 25 to one or several loads. A conventionalvalve 26 serves for the adjustment of the desired rate of air flowthrough or for the closing of the line 24 if no compressed air isrequired. A line 27 for the compressed air branches off from the line 24and leads to the air turbine 3. A conventional valve 28 serves for theopening or closing of the line 27. A line 29 for the relieved air startsfrom the outlet of the air turbine 3 and terminates upstream of themufller 16 in the line 15 for the exhaust gases.

During the operation of the gas turbine unit, a constant quantity ofcompressed air is produced continuously with a predetermined rotationalspeed and is supplied to the load, for example, to a starterinstallation or to a cabin heating installation. If the demand ofcompressed air decreases, then the through-flow quantity is decreased bymeans of the valve 26 and the valve 28 is simultaneously openedcorrespondingly by any conventional known means 30. The excesscompressed air then flows through the line 27 to the air turbine 3 andproduces work in the air turbine 3. The output of the air turbine 3 istransmitted by way of the output shaft 21 to the common multiple inputgear 5 and is therefore rendered useful. The air relieved in the airturbine 3 is admixed to the exhaust gases of the turbine 10 and reachesthe atmosphere by way of the silencer or mufiler 16.

The gas turbine unit according to the present invention permits the fullutilization of the compressed air energy under all types of operations.The independence of the gas turbine process from the compressed airoperation thereby enables additionally a high thermal efiiciency so thata particularly economic gas turbine unit results.

The low-pressure section and the high-pressure section of bine unitwhich not only assures low fuel consumption and the compressor, the gasturbine and theairturbine may be, de-

pending on the design, either of single stage or multi-stageconstruction of the axial or also of the radial type.

The transmission 5 may also be of any known conventional construction.The individual gear wheels thereof may be arranged in the transmission 5in various ways. For example, the gas turbine gear and the air turbinegear may be in meshing engagement with the generator gear. Difieringtransmission ratios, possiblyby the arrangement of intermediate stagesor intermediatetransmission ratios may be utilized between theindividual transmission shafts. Additional shafts, for example, for thedrive of an oil pump, may be provided in the common transmission 5.Furthermore, it is also possible to provide separating clutches, forexample, in order to be able to stop during pure compressed airoperation the generator and the air turbine. The embodiment shown inFIG. 2 has similar parts designated by like numerals which are primed.Inthis embodiment, however, the output shaft 21' of the air turbine 3 isdirectly connected with the output shaft 6' of the gas turbine 10.

Thus, while I have shown and described only these embodiments inaccordance with the present invention, it is understood that the same isnot limited thereto but is susceptible of numerous changes andmodifications as known to those skilled in the art, and I therefore donot wish to be limited to the details shown and described herein butintend to cover all such changes and modifications as are within thescope of those skilled in the art.

I claim:

1. A gas turbine aggregate, especially an auxiliary aggregate for theproduction of mechanical energy and compressed air for aircraft; saidaggregate comprising: compressor means, an output shaft, compressed airline means fed by said compressor means and being operatively connectedwith load means, branch line means operable to be closed and branchingoff from the compressed air line means, the branch line means leading toan air turbine means, and connecting means operatively connecting theair turbine means with the output shaft of the gas turbine, saidconnecting means including transmission means operatively connecting theoutput shaft of the gas turbine and the output shaft of the air turbinemeans with an input shaft of a rotating load, said transmission meansincluding at least two gears which mesh with a third gear, the outputshaft of the gas turbine and the output shaft of the air turbine meansand the input shaft of the load are connected with a respective gear.

2. A gas turbine aggregate according to claim 1, wherein said rotatingload is an electric generator.

3. A gas turbine aggregate according to claim 1, wherein said compressedair line means is operatively connected to said load means via firstvalve means for selectively adjusting the desired air flow rate throughsaid compressed air line means.

4. A gas turbine aggregate according to claim 3, wherein second valvemeans is arranged in said branch line means for the selective opening orclosing thereof, whereby when the demand for compressed air by said loadmeans decreases, said first valve means will decrease the air flow ratethrough said compressor line means and said second valve means will besimultaneously opened so that compressed air flows through said branchline mearm.

5. A gas turbine aggegate according to claim 4, characterized in thatthe compressor means is a multi-stage compressor including a lowpressure section and a high pressure section, said compressed air linemeans branching ofi downstream of the low-pressure section.

6. A gas turbine aggregate according to claim 1, characterized in thatsaid third gear is connected to the gas turbine output shaft.

7. A gas turbine aggregate according to'claim 1, characterized in thatan exhaust line means leading away from the outlet of the air turbinemeans is provided, said exhaust line means being separate from saidcompressed air line means so that the exhaust from the air turbine meansis not connected with said load means, and in that said exhaust linemeans leads to a lowpressure atmosphere such as the exterior of anairplane flying at high altitudes.

8. A gm turbine aggregate according to claim 7, characterized in thatthe compressor means is a multi-stage compressor including alow-pressure section and ,a high-pressure section, the compressed airline means branching off downstream of the low-pressure section.

9. A gas turbine aggregate, especially an auxiliary aggregate for theproduction of mechanical energy and compressed air for aircraft; saidaggregate comprising: compressor means, an output shaft, compressed airline means fed bysaid compressor means and being operatively connectedwith load means, said compressor means being a multi-stage compressorincluding a lowpressure section and a high-pressure section, thecompressed air line means branching off downstream of the low-pressuresection, branch line means operable to be closed and branching off fromthe compressed air line means, the branch line means leading to an airturbine means, and connecting means operatively connecting the airturbine means with the output shaft of the gas turbine, said connectingmeans including transmision means operatively connecting the outputshaft of the gas turbine and the output shaft of the air turbine meanswith an input shaft of a rotating load, said trans mission meansincluding at least two gears which mesh with a third gear, the outputshaft of the gas turbine and the output shaft of the air turbine meansand the input shaft of the load are connected with a respective gear.

10. A gas turbine aggregate according to claim 9, wherein said rotatingload is an electric generator.

11. A gas turbine aggregate according to claim 9, characterized inthatsaid third gear is connected to the gas turbine output shaft.

1. A gas turbine aggregate, especially an auxiliary aggregate for theproduction of mechanical energy and compressed air for aircraft; saidaggregate comprising: compressor means, an output shaft, compressed airline means fed by said compressor means and being operatively connectedwith load means, branch line means operable to be closed and branchingoff from the compressed air line means, the branch line means leading toan air turbine means, and connecting means operatively connecting theair turbine means with the output shaft of the gas turbine, saidconnecting means including transmission means operatively connecting theoutput shaft of the gas turbine and the output shaft of the air turbinemeans with an input shaft of a rotating load, said transmission meansincluding at least two gears which mesh with a third gear, the outputshaft oF the gas turbine and the output shaft of the air turbine meansand the input shaft of the load are connected with a respective gear. 2.A gas turbine aggregate according to claim 1, wherein said rotating loadis an electric generator.
 3. A gas turbine aggregate according to claim1, wherein said compressed air line means is operatively connected tosaid load means via first valve means for selectively adjusting thedesired air flow rate through said compressed air line means.
 4. A gasturbine aggregate according to claim 3, wherein second valve means isarranged in said branch line means for the selective opening or closingthereof, whereby when the demand for compressed air by said load meansdecreases, said first valve means will decrease the air flow ratethrough said compressor line means and said second valve means will besimultaneously opened so that compressed air flows through said branchline means.
 5. A gas turbine aggregate according to claim 4,characterized in that the compressor means is a multi-stage compressorincluding a low pressure section and a high pressure section, saidcompressed air line means branching off downstream of the low-pressuresection.
 6. A gas turbine aggregate according to claim 1, characterizedin that said third gear is connected to the gas turbine output shaft. 7.A gas turbine aggregate according to claim 1, characterized in that anexhaust line means leading away from the outlet of the air turbine meansis provided, said exhaust line means being separate from said compressedair line means so that the exhaust from the air turbine means is notconnected with said load means, and in that said exhaust line meansleads to a low pressure atmosphere such as the exterior of an airplaneflying at high altitudes.
 8. A gas turbine aggregate according to claim7, characterized in that the compressor means is a multi-stagecompressor including a low-pressure section and a high-pressure section,the compressed air line means branching off downstream of thelow-pressure section.
 9. A gas turbine aggregate, especially anauxiliary aggregate for the production of mechanical energy andcompressed air for aircraft; said aggregate comprising: compressormeans, an output shaft, compressed air line means fed by said compressormeans and being operatively connected with load means, said compressormeans being a multi-stage compressor including a low-pressure sectionand a high-pressure section, the compressed air line means branching offdownstream of the low-pressure section, branch line means operable to beclosed and branching off from the compressed air line means, the branchline means leading to an air turbine means, and connecting meansoperatively connecting the air turbine means with the output shaft ofthe gas turbine, said connecting means including transmission meansoperatively connecting the output shaft of the gas turbine and theoutput shaft of the air turbine means with an input shaft of a rotatingload, said transmission means including at least two gears which meshwith a third gear, the output shaft of the gas turbine and the outputshaft of the air turbine means and the input shaft of the load areconnected with a respective gear.
 10. A gas turbine aggregate accordingto claim 9, wherein said rotating load is an electric generator.
 11. Agas turbine aggregate according to claim 9, characterized in that saidthird gear is connected to the gas turbine output shaft.